Gullies on the Central Peak/Pit of Bamberg Crater
Abstract
Bamberg Crater (39.71N, 356.9E) is ~55 km in diameter and situated along the dichotomy boundary, SW of Deuteronilus Mensae, and NE of the outflow channels. Phyllosilicates found in Bamberg in 2012 [1], which require relatively long-term liquid water to develop, indicate the potential for past habitability. This is notable considering Bamberg's relative youth; the ejecta is a Hesperian-Amazonian impact unit, and the crater rims and central peak are stepped, steep, and gullied. Bamberg's central peak is cut asymmetrically by a central pit.
There are pristine gullies on the central peak, and older degraded/buried channels beneath. Of the major peak gullies, avg channel runout is ~1.8 km, and avg slopes [degrees] are 21 (for the overall gully channel), 31 (Alcove), 15 (Apex), and 12 (Apron). Some gully alcoves incise over 10 m into rocky headwalls. Most gullies on this peak originate at ~-4,200 m in elevation. This low elevation site has a max recorded surface pressure of 9.45 mbar (623 TES data points; 39 individual days). Recorded THEMIS surface temperatures approach 273.2 K (75 THEMIS images; 73 of acceptable quality). TES surface temperatures range up to ~279K, ~Ls 107. The present-day surface pressuremight allow for brief periods of liquid water stability on the surface, in a temperature spike. Pitted textures across Bamberg suggest widespread sublimation processes, which, at this pressure, required higher past Amazonian temperatures. Bamberg's central pit may suggest the presence of subsurface volatiles [2, 3]. Lobate moraine-like features in the central pit may contain relict ice. Such lobate arcuate ridges are commonly found below gullies. Other curious lobes located on slopes beside the pit are pitted in texture, perhaps overlying smoother material and a cracked material. Based on our preliminary studies, we propose that much of Bamberg was once liquid water- and ice-rich in the Amazonian, and that while much of the subsurface saturated in this water lost it to sublimation, significant ice in the near-subsurface remains today. Funding provided by 2020 NASA Internship for NG, MRO HiRISE for VG.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMP045.0004G
- Keywords:
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- 1039 Alteration and weathering processes;
- GEOCHEMISTRY;
- 1825 Geomorphology: fluvial;
- HYDROLOGY;
- 5416 Glaciation;
- PLANETARY SCIENCES: SOLID SURFACE PLANETS;
- 5419 Hydrology and fluvial processes;
- PLANETARY SCIENCES: SOLID SURFACE PLANETS